When it comes to body fat, there's fat and then there's belly fat. This is because belly fat – jokingly referred to by many as a "beer belly" but known to doctors by the unpleasant names "visceral fat" and "abdominal obesity" – is closely linked to serious health risks including heart disease, high blood pressure, diabetes, and cancer.

The danger threshold is a 40-inch waistline in men and a 35-inch waistline in women. Anything over these measurements puts a person at risk for developing serious health problems – even those who are obese but currently exhibit none of the usual health risks.

Why is a beer belly so much more dangerous than, say, "thunder thighs?"

Belly fat is smaller and denser than other fats. It churns out hormones and breaks down into fatty acids that flow into your blood stream, drain into the liver, and trigger production of bad cholesterol.

In time, it affects your body's ability to control blood sugar, leading to insulin resistance and "metabolic syndrome." According to the Centers for Disease Control and Prevention, about one-third of the US population over age 20 meets the criteria for metabolic syndrome. This serious condition raises the risk of heart disease and is associated with type 2 diabetes. Check with your doctor to find out whether you have metabolic syndrome, which is tied to your blood pressure, cholesterol and blood sugar levels and a waistline measuring 35 inches or more in women and 40 inches or more in men.

Stay ahead of fat curve

The best way to avoid these dangers? Never gain the weight in the first place. But if your waist measures in the danger zone, recognize your problem, says Dr. Deepa Vasudevan, associate professor of family and community medicine at the University of Texas Health Science Center at Houston.

"If you lose weight, it definitely reduces your risk. There's no doubt about it," she says. "My patients ask me for the magic pill. I would be rich if I had one. Then I ask them, ‘How motivated are you to lose weight and do the right thing?' Until they're mentally ready, I'm not going to be able to do anything."

Blue Cross and Blue Shield's Judy Kolish, a registered dietitian and diabetes educator, says the problem grows with age as people begin to lose muscle mass. That lost muscle often is replaced with fat that settles in the belly. The process is aggravated by stress, which leads a body to release hormones that – you guessed it – leads it to store more fat.

"People sit more and do less," Kolish says. "This reduces their muscle mass even more." The key is to "be as active as you can so you can handle aging optimally," she says. In particular, it's important to do some type of weight training – lifting weights, using resistance bands, or even a few push-ups – and cardio exercise such as walking to help reduce stress. Eating more whole grains, fruits, and vegetables also is an important part of improving your overall health, she notes.

As always, talk with your doctor before beginning any new exercise or diet program. While you're talking with your doctor, ask what your numbers are. If you know your cholesterol, sugar, and blood pressure levels, you can ask specific questions about how best to improve your health.

If losing weight is a challenge, perhaps there are things you can do to lower your blood pressure or cholesterol instead. Every change for the better helps reduce your risk for long-term serious illness, Kolish says.